Marshalling JAXB objects containing lists not working with JEE6 and Java 7

I have a JEE6 application running on Weblogic 12.1.1 and using Java7 (all 64bit) where the JAXB marshalling is not working properly. I don't get an error on the marshal, but the unmarshal fails. This application worked fine using JEE5 on Weblogic 10.3.6 with Java 6. The problem happens when I try to marshal a java object containing a list to an XML string. It seems to be that the marshaller does not know how to marshal the list inside of the object. The marshaller returns the class name instead of the objects in the list. We are using a JAXB bindings file to specify the package name. The list inside of the object is in a different package, but we have mapped (in theory) all of the necessary schema files to the package. Any